#include <stdio.h>
#include <math.h>

int main() {
    double a;
    const double PI = 3.1415926535;
    while (scanf("%lf", &a) != EOF) {
        // 计算球体积
        double b = (4.0 / 3.0) * PI * pow(a, 3);
        printf("%.3lf\n", b);
    }
    return 0;
}